Calibrating practice ball



p 1960 T. BONKOWSKI ET AL 2,953,922

CALIBRATING PRACTICE BALL Filed March 17, 1958 flap/z. L. flalwqawszr,

1N VEN TORS.

By WMW CALIBRATING PRACTICE BALL Teofil L. Bonkowski, 8920 Wonderland Ave'., Los Angeles 46, Calif., and Julius I. Tabach, 10639 Kinnard Ave., Los Angeles 24, Calif.

Filed Mar. 17, 1958, Ser. No. 721,734

Claims. (Cl. 73-379) This invention relates to balls and more particularly to an improved calibrated practice ball which gives a visual indication proportional to the force striking the ball.

It is well known, for example, to provide a relatively hollow, light-weight, plastic golf ball to permit a golfer to practice striking a regulation golf ball when he is confined to a restricted area. Such a prior art practice golf ball will travel a relatively short distance when struck by a golf club due to its light weight and due to its low mass resulting in a very slight momentum. While such a prior art practice golf ball adequately serves to permit a golfer to practice his golf swing as if striking a regulation golf ball, it does not give a golfer any indication of the relative force of his swing.

In accordance with the presently preferred embodiment of this invention there is provided a hollow practice golf ball having an inwardly extending boss affixed to the inner surface of the ball. The boss extends along the diameter of the ball and is of lesser length than the radius of the ball. The boss defines a keyway extending from the outer surface of the ball along the diameter thereof. A pin or key which may be conveniently made of plastic is matable with and disposed within the keyway with a first end of the pin being substantially coextensive with the outer end of the keyway at the outer surface of the ball. opposite or second end of the pin is positioned proximate the inner surface of the ball. The cross section of the pin and keyway are of matable configuration. There is further provided a plurality of calibrating marks along the length of the pin extending from the first end of the pin into the keyway. When the ball is struck with a golf club in such a manner that the second end of the pin receives the force of the striking blow, the pin will be forced a distance through the keyway, which distance is a function of and directly correlated to, the distance a regulation golf ball would have been driven by the same blow as indicated by the calibrated marks extending beyond the outer end of the keyway. While this invention will be described with reference to a practice golf ball, it is equally applicable to any other ball, such as a football, baseball or the like.

his therefore an object of the present invention to provide an improved practice ball which gives a visual indication of the distance of the drive of a comparable regulation ball.

A further object of the present invention is to provide an improved practice golf ball which gives a visual indication of the distance of the drive of a comparable regulation galf ball.

Another object of the present invention is to provide an indicator in combination with a practice golf ball to register a reading of the distance which a regulation golf ball would have travelled had it been struck with the same force which was imparted to the practice golf ball.

The novel features which are believed to be characternite rates atent The pin is of such length that the EQQ istic of the present invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

In the drawing:

Figure 1 is a view in perspective showing a practice golf ball in accordance with the present invention resting on a golf tee which ball is about to be struck with a golf club;

Figure 2 is a view, partly in section, of the practice golf ball of Figure 1;

Figure 3 is a cross-sectional view taken along line 33 of Figure 2;

Figure 4 is a partial end view of the practice golf ball according to the present invention taken along line 44 of Figure 2; I

Figure 5 is a cross-sectional view, drawn to a smaller scale than Figure 2, of the ball of Figure 1 showing how it will appear at the moment of impact; and

Figure 6 is a cross-sectional view of the ball of Figure 1 showing how it will appear after impact.

Referring now to the drawing, there is shown in Figure 1 a practice golf bail 11 which may be made of plastic or any other strong and resilient light-weight mate? rial, in accordance with the presently preferred embodiment of this invention. The ball 11 is shown tobe disposed upon a golf tee 15..

Golf club 10, shown in phantom, depicts a golf club which is about to strike the ball 11 as it is swung by a golfer along the line indicated by the arrow 14. The ball has provided about the surface thereof a plurality of holes 20 to reduce the weight of the ball.

A pin 12, which is made of plastic, is shown in Figure 2 to be disposed within the hollow central portion 21 of the ball 11 in accordance with the present invention. The ball 11 basically consists of two hollow hemisphere sections 23 and 24. Within section 24 and extending toward the center of the ball is an inwardly extending boss 16 which defines a keyway whose cross-sectional configuration may best be seen in Figure 3, it being shown there as triangular in shape. Pin or key member 12 has a cross-sectional configuration which is matable with that of the keyway 16. Along the pin 12 are provided a series of calibrating marks 30 extending from, the first end of the pin inwardly along the pin. While the two half sections 23 and 24 are apart, pin 12 is placed into the keyway 16 so that the end 25 of the pin is tangent with the outersurface of the ball. The inwardly extending length of the boss and keyway is sufiicient to constrain the pin to radial movement while being sufficiently short to allow full travel of the head 28 upon deformation of the ball as described hereinafter.

A hole 27 having a generally circular cross-sectional configuration is provided in the ball, the center of the hole being coincident with the diameter along which keyway 16 lies. other end of pin 12. Further, a fillet 29 is included at the base of the head 28 to give greater Strength thereto. The length of pin 12 is made equal to the outside diam to the surface of the golf ball at this point.

A dome shaped head 28 is provided at the ing against the inner surface of the ball or possibly extending to a point short of contact therewith.

In use the ball 11 is placed upon the tee 15 in such a manner that the dome shaped head 28 faces the club. Thus, if a perfect blow is struck the ball, the fullest impact force will be imparted *to the "pin 12. 'O'fcourse, the ball will also be caused to deform -by the blow as 'is shown in Figure 5. 'Thefit between the pin "12 and keyway 16 and the coefiioient of friction Iesultingtherebetween isso chosen that the pin will be'force'd through :the keyway a distance substantially equal to the displacement of the deformed surface of "the ball. The coeffi- 'cient of friction between the pin .12 and the keyway 16 may be altered by having less than all of the peripheral surface of the pin in engagement with the walls of the 'keyway. That is,'the pin may, for example, have a substantially triangular cross-section, the corners thereof being rounded while the keyway may have a circular cross-section as shown in the drawing. The marks 30 are 'so calibrated as to give adirect reading of the distance a regulation golf ball would have travelled had it been struck-the same blow. Thus, after impact when the ball has again assumed its .normal shape as shown in Figure 6, the pin 12 will remain extended the distance of displacement.

In choosing the proper materials for the ball and pin memberywhich materials neednt necessarily be the same, what is important is that they be of sufiicient strength and toughness to withstand repeated impact while .returning to shape. Further, the materials must be such that fusion does not take place between the pin and the ball on impact.

There has thus been described a'new and novel practice golf ball which gives a visual indication of the force of the blow striking the ball which is directly related to the distance a regulation golf ball would have travelled. Variations in the shape of the pin and its associated'keyway may be made without departing from the spirit of the invention, while a generally'triangular shape has been shown, any other shape may be conveniently employed.

Further, while this invention has been described with reference to a practice golf ball, it may also be applied to any other practice ball, such as a baseball, football or the like, without departing from the'spirit of the invention.

What is claimed is:

l. A practice golf ball which when struck registers a visual indication of the distance a regulation ball would travel when struck by the same force imparted to said practice ball including: a deformable b'all; a'pin member disposed within said ball, said pin member having first and second ends, said pin member being supported toward said first end by a matable openingwithin said ball, said pin member being in frictional engagement with the wall ofsaid-opening butpermitting said pin to slide therethrough when said pin is struck at said second end by a force great enough to overcome the friction between the contacting periphery of said pin member and the inner surface ofsaid wall, said pin member having calibrating marks disposed on thesurfacethereof.

2. A resilient practice ball which "when struck registers a visual indication of the distance-"a'regulation ball'wonld travel if struck by the same force imparted to said ,practice ball, said ball defining *inter'iorly thereof a keyway extending at least partially 'alonga diameter of saidrball,

said keyway having a predetermined 'cross section'al' configuration defining an open'ingat the surface of's'aidball, a key rneniber, the cross-sectional configuration of "said key member being s'lidably matable with that of said keyway, said key member being disposed within said keyway and hav'ingone-end ofsaid key member substantially coincident withthesurface of'said hall within said opening when said ball is in the relaxed condition, said key member having calibrating marks disposed on the surface thereof such that deformation of said ball changes the position of said key member within said keyway.

3. In a hollow light-weight deformable practice ball having two holes at opposite ends of a diameter of said ball, a pin member disposed within said ball, the length of said pin member being substantially equal to the outside diameter of said practice ball, said pin member having a dome shaped head at oneend thereof, the top surface of which extends into one of said holes and which is coextensive with the outer surface of said ball, the second end of .said pin being 'matabl-y slidable and in frictional engagement with the inner wall of the other of such holes at the opposite endofsaid ball means for supporting said pin member within said other hole, said second end of said pin having calibrating marks correlating the relative displacement of .said pin member .in rthe vicinity of said head whereby the ball .is-deformed-causing said pin member to be partially driven through the other hole with the expectant distance of travel of a regulationballwhen said ball is struck.

4. -In a hollow light-weight deformable practice ball having two diametrically opposed holes therein, a pin member having one end thereof mateably slidab'ly fitted through one of said holes, :means for supporting said pin member within said one hole, there being :a prededetermined coefficient-of friction therebetween, tthe :length of :said pin member being substantially equal to lthe outside diameter of said ball, said pin member having a'dome shaped head at theother end thereof, and asen'es of calibrating marks being disposed on said one end of said pin, said marks being adapted to correlatethe relative displacement of said 'pin member with the expectant distance-of travel of a regulation ball *when said practice ball is-struck by a predetermined force in the vicinity of said head whereby the ball :is deformed oausingsaid pin member to be partially driven throughlsaid :one :hole.

5. A practice :ball which when struck :registers a'visual indication of the applied striking force including the combination :of: .a hole provided in the surface of said ball; a:lceyway integral with the inner surface of said ball, said keyway having 'a predetermined crosssection'al con figuration, the center line of .said keyway bein'g coincident with the diameter of said ball; :a :pin member having a first end vand zaisecond end, the first end of said pinmcmberhavinga series-of parallel calibration marks, the cross sectional configuration of said pin member being matable lwith that-of said keyway, said first "end of said key member being fitted within said keyway =and extending therein so that the end thereof is parallelwith the outer surface of said -ball, the second -en'd-of said pin member having a substantially dome shaped h'ead, said head being disposed within said hole so that the top surface of said head iscoincident with the outer surface-of said ball, said pin member-being of a length equal to the diameter of said ball, said pin member further being adapted -'to he driven a predetermined displacement through said keyway when said ball is struck with the dome of said pin member being in line with thestriking force, said disp'lacement being correlated to the distance a regulation iball would have travelled if it had been struck by the same force.

References Cited in the file of this patent UNIT-ED STATES PATENTS 1,538,654 Reach May 19, 1925 1,72'11041 Ro'ternrund July 16, I929 2223;647 Stumpf Dec. '3, 1949 

